A stress measuring method and a stress measuring device by the use of photoluminescence such as a Raman spectroscopy have been well known. The spectroscopy by the use of photoluminescence, namely, a photoluminescence spectroscopy has a resolution in units of μm and is used for measuring a stress or the like in an elastic material.
A stress measuring method and a stress measuring device by the use of the Raman spectroscopy are open to public, for example, in an official gazette of Japan Patent Laid-open Number 7-19969, Japan Patent Laid-open Number 6-347343, and Japan Patent Laid-open Number 8-5471.
A stress measuring method comprising a laser luminous source, an objective lens for narrowing down the laser light in a shape of a spot on a surface of an object whose stress is to be measured, a half mirror for introducing the scattered light into a spectrometer, and a spectroscopy is open to public in the above official gazettes.
However, the stress measuring by the use of the above Raman spectroscopy has a problem such that a positional resolution is low.
More specifically, there is a limit to narrowing down a diameter of a beam spot of the laser light when the light is irradiated on a specimen for the stress measuring method by the use of the above Raman spectroscopy. For example, the positional resolution of the stress measuring method by the use of the Raman spectroscopy is about 1 μm and the positional resolution of the stress measuring method by the use of proximity field light is about 200 nm.
Recently, a new material is manufactured such as a nanotube or a nanocoil having a minute structure wherein atoms/molecules are arranged in a level of nano-technology. Since the conventional stress measuring method by the use of the Raman spectroscopy can not narrow down a beam spot diameter and is low in a positional resolution, in case of measuring a stress of the new material in the level of nano-technology (for example, about several nm) wherein a recurring unit size of the new material is mostly not over 200 nm, the stress of a local portion (nano level) can not be measured because an average stress of whole of the beam spot area is obtained.
As a result of this, in case that a high stress concentration is applied to an extremely small area, for example, in nano level, the stress concentration can not be detected because the stress is measured on a basis of an average value, resulting in failure in determining a cause of break-down.
Especially in a field of a stress measurement, increasing the positional resolution contributes to not only improving an accuracy of localization but also enabling measurement of high stress concentration on a local area that has not been measured by a conventional method, which will make a rapid progress in clearing up a cause of break-down or measuring physicality.
Furthermore, stress sensitivity tends to be low and it is difficult to measure a minute stress change in the conventional stress measuring method by the use of the Raman spectroscopy.
The present claimed invention intends to provide a stress measuring method and a stress measuring device high in a positional resolution and superior in stress sensitivity.